Cann't get the invalid-tip works when using form fields in a Poped-up Dialog

Cann't get the invalid-tip works when using form fields in a Poped-up Dialog

this issue really bother us so bad, when we use form fields in a poped-up Dialog(yes, we're using 1.1.1), the 'Invalid-tip' does not work in whatever you set the 'Ext.form.Field.prototype.msgTarget' to 'qtip' or 'side', it only works with 'under' mode.
The field marked to invalid with red red frame(default style), but the invalid-tip does not pop up when mouse over, and I checked DOM with FireBug, seems no div be created or be changed when I move mouse above the fields, which does do something when not use these fields in a Dialog(some div which holds the invalid-tip while be modified with adding some css class).